Interaction between supercritial carbon dioxide-cosolvent and poly(vinyl acetate)

doi:10.11949/j.issn.0438-1157.20170900

Abstract

Abstract:

The effect of cosolvents (ethanol, acetone, n-heptane) on the supercritical CO₂ system were evaluated through the multi-scale molecular modeling and dissolution behavior measurement, which might improve the solvent-solvent and solvent-solute interactions and enhance the compatibility with polymer. The ab initio calculation showed that the interaction between ethanol and CO₂ was the strongest one, followed by that of acetone and n-heptane. The molecular dynamics simulations indicated that ethanol significantly increased the solubility parameter of solvent, and the interaction of supercritical CO₂-ethanol with PVAc chain was stronger than that of the other two at the same co-solvent content, which was helpful to improve the compatibility between PVAc and the solvent. The interaction between ethanol and CO₂ was the strongest due to the bigger solubility parameter of ethanol and the obvious hydrogen bond between ethanol and CO₂.The cloud point experiments confirmed that ethanol was the most effective to reduce the cloud point pressure of PVAc. The addition of cosolvent enhanced the compatibility of supercritical CO₂ system with PVAc, and the solubility of PVAc in supercritical CO₂-cosolvent increased with the mole fraction of cosolvent.

Key words: carbon dioxide, cosolvent, poly (vinyl acetate), solubility, molecular simulation

摘要：

采用多尺度模拟和实验结合研究了乙醇、丙酮、正庚烷等共溶剂的加入对超临界二氧化碳（CO₂）溶剂体系的影响，通过改善溶剂-溶剂和溶剂-溶质相互作用增强聚醋酸乙烯酯（PVAc）与CO₂的相容性。量子力学从头算结果表明，3种共溶剂中乙醇与CO₂的相互作用最强，丙酮次之，正庚烷最弱。分子动力学模拟也表明在相同共溶剂含量下，乙醇对溶剂体系溶解度参数的改善最为明显，超临界CO₂-乙醇体系与PVAc链的相互作用更强，有助于提高PVAc与溶剂的相容性。这是由于乙醇本身的溶解度参数较大，且与CO₂形成氢键作用，从而大幅增强了其与CO₂的相互作用。浊点压力实验证实了共溶剂的加入增强了超临界CO₂体系与PVAc的相容性，乙醇的加入对PVAc浊点压力的降低最为有效，且随着共溶剂含量的增加，PVAc在溶剂中的溶解能力增强。

关键词: 二氧化碳, 共溶剂, 聚醋酸乙烯酯, 溶解性, 分子模拟

CLC Number:

TQ021.2

HU Dongdong, BAO Lei, LIU Tao, LANG Meidong, ZHAO Ling. Interaction between supercritial carbon dioxide-cosolvent and poly(vinyl acetate)[J]. CIESC Journal, 2018, 69(2): 555-562.

胡冬冬, 包磊, 刘涛, 郎美东, 赵玲. 超临界二氧化碳-共溶剂体系与聚醋酸乙烯酯相互作用[J]. 化工学报, 2018, 69(2): 555-562.

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